3/3/3 Tesla vector rotate magnet system with optical access

This custom-designed vector rotate magnet system differs from the usual vector rotate configuration by featuring three orthogonal split pair magnet coils, rather than the more conventional solenoid with one or two orthogonal split pair coil sets. This is in order to offer straight-through optical access in the horizontal (x and y) axes, with perpendicular sample access and loading in the vertical z axis into a 1.5 K ‑ 300 K variable temperature insert (VTI).

Despite its apparently ‘low’ field, the magnet design is not trivial, due to the large twisting forces set up between the coils in their different vector combinations. Careful three-dimensional stress analysis enabled a successful design in which the magnet can be run to any vector up to 3 Tesla magnitude within a complete 360º sphere.

To fit the magnets in a compact arrangement, the z-, y- and x-axis coil pairs are nested inside each other as shown below. Each pair of coils is fitted with its own persistent mode switch.

The cryostat is a low loss Oxford Instruments design for optical and beamline applications. To reduce the number of optical elements in the beam path, the radiation shield has no windows but is fitted with re-entrant bore tubes to reduce the radiative heat load. This cryostat design can also be supplied as a zero-boiloff helium recondensing system.